Analyzing the propagation effect of high-speed rail from air passenger to air cargo traffic in China

The profound influence of high-speed rail (HSR) on air transportation has attracted widespread recognition. Considering that the air cargo in China is primarily transported in belly holds of passenger planes, the impacts of HSR entry on air cargo traffic are highly correlated with air passenger traffic. That is, there exists a propagation effect from HSR impacts on air passenger to cargo. Although existing studies have separately analyzed the impacts of HSR on air passenger and air cargo traffic, none of them investigate the propagation effect. To address this research gap in the literature, we propose to analyze the propagation effect of HSR from air passenger traffic to air cargo traffic. Specifically, we develop a hierarchical panel regression model to capture the propagation effect. We use dummy variables representing the opening HSR services to capture the impacts of HSR on air passenger traffic and air cargo traffic at the lower level. At the upper level, we employ a structural equation incorporating the coefficients of HSR dummy variables from air passenger and air cargo, along with other relevant determinants, to examine the propagation effect. We undertake a case study utilizing annual data on air passenger traffic and air cargo traffic in China, using a dataset of 233 city pairs spanning the period from 2001 to 2019. Our results reveal a significant propagation effect: 66.89% of HSR-induced passenger traffic reduction propagates to air cargo. Moreover, 60% of cargo traffic heterogeneity stems from this propagation, with backbone network and regional factors explaining an additional 25.4%.